Delay completing marking (and thus the atomic GC pause) during JS
executions, increasing the chance to finalize the garbage collection
from a task. This is beneficial as it avoids stack scanning which is
expensive and can keep alive outdated objects in case of unified heap.

Completing will be delayed at most by some overshoot factor (10%).

In addition, the GC keeps the weighted average of previously recorded
time to incremental marking task invocations and bails out if the
task is expected to arrive too late.

Bug: chromium:1044630
Change-Id: I10e63e6aaa88d8488d4415f311016dce2b4e62a2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2030906
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66107}